<template>
        <canvas class="bgCanvas" width="100%" height="100%"></canvas>
</template>

<script>
export default { // es6的暴露
// 挂载之后的钩子函数  画canvase
  mounted:function(){
      //挂载后执行的方法
//    获取canvas
        var canvas = document.getElementsByClassName('bgCanvas')[0],
        	ctx = canvas.getContext('2d'); //2d的画板
//    设置宽高
          canvas.width = window.innerWidth;
          canvas.height = window.innerHeight;

          ctx.lineWidth = .3;

          ctx.strokeStyle = (new Color(150)).style;
          var dotsNomber = 400;// 点点数
          if(canvas.width < 1400){
        	  dotsNomber = 200;
          }

          var mousePosition = {
        	x: 30 * canvas.width / 100,
        	y: 30 * canvas.height / 100
          };

          var dots = {
        	nb: dotsNomber,
        	distance: 100,
        	d_radius: 150,
        	array: []
          };


          function colorValue(min) {//255-0
        	return Math.floor(Math.random() * 255 + min);
          }

          function createColorStyle(r,g,b) {// 颜色的rgba的表示方法
        	return 'rgba(' + r + ',' + g + ',' + b + ', 0.8)';
          }

          function mixComponents(comp1, weight1, comp2, weight2) {
        	return (comp1 * weight1 + comp2 * weight2) / (weight1 + weight2);
          }

          function averageColorStyles(dot1, dot2) {
        	var color1 = dot1.color,
        		color2 = dot2.color;

        	var r = mixComponents(color1.r, dot1.radius, color2.r, dot2.radius),
        		g = mixComponents(color1.g, dot1.radius, color2.g, dot2.radius),
        		b = mixComponents(color1.b, dot1.radius, color2.b, dot2.radius);
        	return createColorStyle(Math.floor(r), Math.floor(g), Math.floor(b));
          }

          function Color(min) {
        	min = min || 0;
        	this.r = colorValue(min);
        	this.g = colorValue(min);
        	this.b = colorValue(min);
        	this.style = createColorStyle(this.r, this.g, this.b);
          }

          function Dot(){
        	this.x = Math.random() * canvas.width;
        	this.y = Math.random() * canvas.height;

        	this.vx = -.5 + Math.random();
        	this.vy = -.5 + Math.random();

        	this.radius = Math.random() * 2;

        	this.color = new Color();
        	//console.log(this);
          }

          Dot.prototype = {
        	draw: function(){
        	  ctx.beginPath();
        	  ctx.fillStyle = this.color.style;
        	  ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2, false);
        	  ctx.fill();
        	}
          };

          function createDots(){
        	for(var i = 0; i < dots.nb; i++){
        	  dots.array.push(new Dot());
        	}
          }

          function moveDots() {
        	for(var i = 0; i < dots.nb; i++){

        	  var dot = dots.array[i];

        	  if(dot.y < 0 || dot.y > canvas.height){
        		dot.vx = dot.vx;
        		dot.vy = - dot.vy;
        	  }
        	  else if(dot.x < 0 || dot.x > canvas.width){
        		dot.vx = - dot.vx;
        		dot.vy = dot.vy;
        	  }
        	  dot.x += dot.vx;
        	  dot.y += dot.vy;
        	}
          }

          function connectDots() {
        	for(var i = 0; i < dots.nb; i++){
        	  for(var j = 0; j < dots.nb; j++){
        		var i_dot = dots.array[i];
        		var j_dot = dots.array[j];

        		if((i_dot.x - j_dot.x) < dots.distance && (i_dot.y - j_dot.y) < dots.distance && (i_dot.x - j_dot.x) > - dots.distance && (i_dot.y - j_dot.y) > - dots.distance){
        		  if((i_dot.x - mousePosition.x) < dots.d_radius && (i_dot.y - mousePosition.y) < dots.d_radius && (i_dot.x - mousePosition.x) > - dots.d_radius && (i_dot.y - mousePosition.y) > - dots.d_radius){
        			ctx.beginPath();
        			ctx.strokeStyle = averageColorStyles(i_dot, j_dot);
        			ctx.moveTo(i_dot.x, i_dot.y);
        			ctx.lineTo(j_dot.x, j_dot.y);
        			ctx.stroke();
        			ctx.closePath();
        		  }
        		}
        	  }
        	}
          }

          function drawDots() {
        	for(var i = 0; i < dots.nb; i++){
        	  var dot = dots.array[i];
        	  dot.draw();
        	}
          }

          function animateDots() {
        	ctx.clearRect(0, 0, canvas.width, canvas.height);
        	moveDots();
        	connectDots();
        	drawDots();

        	requestAnimationFrame(animateDots);
          }
           canvas.onmousemove=function(e){
                    mousePosition.x = e.pageX;
                    mousePosition.y = e.pageY;
                    }
            canvas.onmouseleave= function(e){
                mousePosition.x = canvas.width / 3;
                mousePosition.y = canvas.height / 3;
               }

          createDots();
          requestAnimationFrame(animateDots);
  }
};



</script>


